Illumination of surfaces with radiant energy has been used in surface treatments such as treatments related to curing, polymerization, oxidation, purification, disinfection, and sterilization. Generally, radiant energy is the energy of electromagnetic waves. The electromagnetic waves typically are classified into types according to the frequency of the electromagnetic waves. These types include (in order of increasing frequency): radio waves, microwaves, terahertz radiation, infrared radiation, visible light, ultraviolet light, X-rays, and gamma rays. Examples of such surface treatments include irradiating a surface with radiant energy to polymerize monomers to create a polymer coating on the surface. A surface may be irradiated with radiant energy to cure or crosslink a polymer on the surface. It is also known to irradiate a surface with radiant energy to disinfect or sterilize the surface.